The present invention relates to an actuator for operating an access door on an aeroplane, of the type comprising a body fitted with a motor member and with a drive member that is movable relative to the body under the action of the motor member. It also relates to a motorized access door on an aeroplane.
In present-day aeroplanes, access doors to the luggage compartment, or the passenger access doors to the interior of the cabin are operated by hydraulic actuators which move the closing panels between a position in which the passage is closed off and a withdrawn position in which the passage is opened.
In the remainder of the description the term xe2x80x9cdoorxe2x80x9d is used to indicate any door or flap or other movable member for closing a passage, such as the doors giving access to the propulsion components of an aeroplane.
The actuators currently used for this application are hydraulic actuators which work by means of a ram powered by a hydraulic fluid under pressure.
With a hydraulic actuator, when the closing panel is in its closed position, the supply of hydraulic fluid to the actuator is cut off. The ram built into the hydraulic actuator now exerts only a very small load, so that the closing panel can, even in the absence of power, or in the event of serious accidents on the aeroplane, be shifted manually by the crew or rescue teams, without the hydraulic actuator""s locking the panel and preventing it from being moved.
Of course, in order to prevent any unintentional opening of the doors when the aeroplane is in flight, additional locking means are provided to prevent movement of the closing panel.
In addition, the actuator must not introduce any stress into the aeroplane structure once the door is closed. For this purpose the hydraulic control circuit of the hydraulic actuator is opened to cause a pressure drop in the actuator.
Hydraulic actuators perform satisfactorily. However, they require a source of pressurized hydraulic fluid and pipework to convey the fluid to each actuator. The network of pipes increases the complexity of the aeroplane.
It is an object of the invention to provide an alternative solution to hydraulic actuators for controlling the access doors of an aeroplane, in which the load exerted by the actuator is small when the actuator stops.
To this end the subject of the invention is an actuator for operating an access door on an aeroplane of the aforementioned type, characterized in that the motor member is an electric motor, and in that mechanical means of movement transmission are mounted inside the body between the electric motor and the drive member to drive the said drive member from the electric motor, which transmission means comprise means of mechanical disengagement of the electric motor from the drive member, which, after disengagement, allow the drive member to be moved independently of the electric motor.
In certain particular embodiments, the actuator comprises one or more of the following characteristics:
the means of disengagement comprise a positive clutch and means of operating the positive clutch to move it between an engaged position and a disengaged position;
the complementary parts of the positive clutch are carried in one case on a pinion of the transmission means, and in the other case on a transmission shaft along which the pinion can slide between the engaged position and the disengaged position, which pinion is free to rotate on the said shaft when not engaged;
the said positive-clutch operating means comprise an electromagnet;
it comprises means for detecting when the door is closed, and the means of disengagement are such as to mechanically disengage the electric motor from the drive member (24) when it is detected that the door is closed;
the said detection means comprise a sensor mounted on the body to detect an extreme position of the drive member; and
the said transmission means comprise a screw and nut arrangement for the translational drive of the said drive member relative to the body from the rotary movement of the electric motor.
The invention also relates to a motorized access door on an aeroplane, characterized in that it comprises a closing panel that can be moved relative to the structure of the aeroplane, between a position in which it closes an opening, and a position of disengagement from this opening, and an actuator as described above for moving the said closing panel, the door also comprising means for activating the actuator disengaging means when the closing panel is in the closed position.
In certain particular embodiments, the access door comprises one or more of the following characteristics:
it comprises means for locking the closing panel in the closed position.
A clearer understanding of the invention will be gained from reading the following description given purely by way of an example and with reference to the accompanying drawings in which: